Summary [2 m+ and [2m°] yeast were transformed to stable leucine prototrophy with the hybrid yeast — E. coli plasmid, pJDB219. This plasmid contains the entire sequence of the endogenous 2 m yeast DNA plasmid in addition to the yeast nuclear LEU2+ gene and the Co1E1 derivative, pMB9. In the [2 m+] transformants, a new wholly yeast LEU2+ plasmid, pYX, was generated, probably by a recombination event between pJDB219 and 2 m DNA. The plamid, pYX, in the absence of 2 m DNA, was found to exist in equimolar amounts of two forms, A and B, which probably arise by intramolecular recombination across the inverted repeat sequences of the 2 m DNA portion of the plasmid. pJDB219 was found to require the presence of 2 m DNA to undergo this intramolecular recombination. The results suggest that 2, m DNA and pYX code for a gene product required in this recombination event which pJDB219 cannot produce. 相似文献
The impact of hydrosalpinx (HSPX) on in-vitro fertilization (IVF) outcome
has recently been the subject of intense debate. Most, but not all, studies
have reported decreased implantation and pregnancy rates and increased
early pregnancy loss in HSPX patients. This has led to prophylactic
salpingectomies prior to IVF in HSPX patients despite the lack of any
prospective studies to suggest that any improvement will occur. Women with
HSPX constitute a heterogeneous population because some conceive easily
with IVF while others do not until after surgical correction. HSPX also
increases in size with ovarian stimulation, and can cause implantation
failure by fluid reflux into the uterine cavity. Careful assessment of the
endometrial lining is mandatory in HSPX to rule out fluid reflux from the
HSPX. We present two case reports of patients whose HSPX enlarged with
ovarian stimulation, causing fluid reflux into the uterine cavity which was
only noted after human chorionic gonadotrophin (HCG) administration.
相似文献
We isolated bacteria from ticks, lice and fleas. Partial small subunit rRNA sequences were obtained for each isolate and the closest matches in the FastA database were determined. These bacteria were mostly Gram-positive (Firmicutes), although representatives from the Proteobacteria (alpha, beta, gamma subdivisions) and CFB group were also isolated. Most of the isolates we found were from genera that were present in most of the ectoparasites studied, but a few genera were restricted to one species of ectoparasite. The most commonly isolated genera were Stenotrophomonas, Staphylococcus, Pseudomonas, Acinetobacter and Bacillus. Species of Bacillus and Proteus, which have biopesticide potential, were found in some of these ectoparasites. Overall, the communities of bacteria were similar to those found in other studies of parasitic arthropods. 相似文献
INTRODUCTION: There are important differences in rural, regional and urban general practice environments. The purpose of this study was to articulate models that explain career satisfaction among general practitioners (GPs) in these practice environments. METHODS: Of 4958 eligible physicians across Canada, 2810 (56.7%) completed a 12- page survey between January and March 2004, from whom a total of 256 GPs in rural, regional and urban communities were selected. Response bias was checked and found to be negligible. We used hierarchical regression analysis to record cumulative R2, standardized beta and significance levels as each predictor was entered. We applied weighting factors to reflect the actual physician population in Canada. RESULTS: The models explained 88.5% of the variance in career satisfaction for GPs in small towns, 88.9% for GPs in regional communities and 86.3% for GPs in urban cities. The explanatory variables consisted of distress and coping, role in community activities, the quality of health care services and access to them, intrinsic and extrinsic rewards, workload and organizational structure. CONCLUSION: Career satisfaction for small-town doctors is associated with being able to cope with stress in handling a wide variety of clinical conditions, largely on their own, but with effective collaboration from physicians in larger centres. Rural GPs also enjoy academic responsibilities. Satisfaction for GPs in regional communities also depends on coping with stress and the ability to maintain an efficiently operating set of secondary- level health services in their community. Satisfaction for urban GPs is associated with collegiality, which dampens stress, and access to a full range of health services, including community, hospital, mental health and rehabilitation services. Career satisfaction for all GPs is associated with equity, manageable workloads and effective practice management; however, all of these professional issues contribute, in small increments, to satisfaction. 相似文献
Prior studies have identified a complicated pattern of interspecific hybridization between members of the Aedes (Stegomyia) scutellaris (Walker) mosquito group, which includes medically important vectors of bancroftian filariasis and dengue. Here, we report that two members of the group, Aedes polynesiensis Marks and Aedes riversi Bohart & Ingram, are both infected with intracellular Wolbachia bacteria. Sequencing of the Wolbachia wsp gene demonstrates that the infections differ from each other and from Wolbachia infections previously reported in mosquitoes. Aedes polynesiensis is the first mosquito identified with a wMel Wolbachia type. Intraspecific crosses of infected and aposymbiotic lines generated via antibiotic treatment show that the Wolbachia infections in both species cause high levels of cytoplasmic incompatibility. Interspecific crosses show that the two species are reproductively isolated. However, repeating the interspecific crosses with aposymbiotic mosquito strains demonstrates that the Wolbachia infections play a role in preventing hybrid offspring. We discuss Wolbachia infections in relation to better defining the evolutionary relationships and causes of speciation within the group, understanding the basis for the observed east-to-west gradient in filarial refractoriness, and developing novel genetic control measures. 相似文献
Serum samples were collected from 328 healthy American Blacks and from 61 American Blacks with systemic lupus erythematosus (SLE). Sera were typed for the Gm1,2,3,5,6,13,17, and 21 allotypes as well as for the Km(1) allotype. The frequency of Gm phenotype 1,17;5,6,13 was significantly increased in the SLE patients (p = 0.0001, RR = 3.19, EF = 0.29). Our data suggest the existence of at least two immunoglobulin allotype associated genes that somehow interact to increase susceptibility to SLE in Blacks. To our knowledge, this is the first report of an association of Gm and SLE in Blacks. 相似文献
In the current research, we investigated perceptual accuracy in romantic partners’ detection of sexual rejection. In two daily diary studies of predominantly cisgender heterosexual couples, we examined patterns of accuracy and bias concerning both the degree of sexual disinterest (Study 1; N?=?98 couples) and occurrence of sexual rejection (Study 2; N?=?115 couples), as well as how these perceptions were associated with satisfaction. Using a multi-method approach to capture both continuous and categorical operationalizations of sexual rejection (Study 1: truth and bias; Study 2: quasi-signal detection), we found that people were both accurate and biased in their perceptions of partner rejection. Across studies, results showed that people demonstrated general tracking accuracy in detecting a partner’s sexual rejection, but they also overestimated the degree and occurrence of this rejection. Additionally, this overestimation bias was associated with lower daily relationship and sexual satisfaction. Overall, our findings highlight the importance of dyadic perceptions of sexual rejection in shaping daily relationship and sexual functioning.
Summary
Background & Aims: Epidemiological studies suggest that antioxidant polyphenols in the human diet may protect against diseases such as cancer.
In this study we investigated the cytoprotective potential of the flavonoids, quercetin, myricetin, kaempferol and rutin against
oxidative DNA damage in human colonocytes in vitro.
Methods: Caco-2 cells, which display specialised enterocyte/colonocyte cell functions, were used as an in vitro model for human colonocytes. Hydrogen peroxide was employed as the oxidant. DNA damage (strand breakage, oxidised purines
and oxidised pyrimidines) was determined using the alkaline single cell gel electrophoresis or comet assay. Cell growth and
viability were measured.
Results: Hydrogen peroxide caused a dose-dependent increase in DNA strand breakage in human colonocytes, presumably via oxygen free
radical generation. Quercetin and myricetin protected Caco-2 cells against oxidative attack. In addition, quercetin decreased
hydrogen peroxide-mediated inhibition of growth. Neither rutin nor kaempferol was effective. However, quercetin, while inhibiting
DNA strand breakage, did not alter the levels of oxidised bases following peroxide treatment. The antifungal agent ketoconazole,
prevented quercetin cytoprotection in Caco-2 cells, indicating that P450-mediated metabolism may alter the efficacy of the
flavonoids against oxidative DNA damage.
Conclusion: Flavonoids, particularly quercetin, the most abundant flavonoid in the human diet, are likely to be important in defending
human colonocytes from oxidative attack.
Received: 7 October 1998, Accepted: 5 November 1998 相似文献